AI Summary

Microplastics, defined as particles between 1 and 5,000 micrometers, originate mainly from the breakdown of larger plastics and from products such as paints and cosmetics. They are detected in nearly every part of the planet. A new study published in the journal *Science* indicates that rivers may transport a greater quantity of these particles into the ocean than previously estimated. The research highlights the need to reassess the scale of riverine microplastic inputs to marine ecosystems.

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